package middleware

import (
	"fmt"
	"log"
	"math/rand"
	"net/http"
	"runtime/debug"
	"time"

	"github.com/gin-gonic/gin"
)

// ErrorHandler middleware for proper error handling
func ErrorHandler() gin.HandlerFunc {
	return func(c *gin.Context) {
		defer func() {
			if err := recover(); err != nil {
				// Log the panic with stack trace
				log.Printf("Panic recovered: %v\n%s", err, debug.Stack())
				c.Error(err.(error))
				c.JSON(http.StatusInternalServerError, gin.H{
					"error": "Internal server error",
					"message": "Something went wrong. Please try again later.",
					"request_id": c.GetString("request_id"),
				})
				
				c.AbortWithStatus(http.StatusInternalServerError)
			}
		}()
		
		c.Next()
	}
}

// RequestID middleware for tracking requests
func RequestID() gin.HandlerFunc {
	return func(c *gin.Context) {
		requestID := c.GetHeader("X-Request-ID")
		if requestID == "" {
			requestID = generateRequestID()
		}
		c.Set("request_id", requestID)
		c.Header("X-Request-ID", requestID)
		c.Next()
	}
}

func generateRequestID() string {
	// Simple request ID generation
	return "req_" + timestamp() + "_" + randomString(8)
}

func timestamp() string {
	return fmt.Sprintf("%d", time.Now().Unix())
}

func randomString(length int) string {
	const charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
	b := make([]byte, length)
	for i := range b {
		b[i] = charset[rand.Intn(len(charset))]
	}
	return string(b)
}